1. Field of the Invention
The present invention relates to methods and apparatus for mechanical harvesting of fruit and the like, and more particularly to a robotic fruit harvester utilizing optical location of pickable fruit. My invention is particularly suitable for harvesting of citrus fruit.
It is estimated that over one million acres in the United States is devoted to producing citrus trees having an on-tree value exceeding $1 billion. About 25% of the United States citrus crop is for fresh fruit, with the remainder processed for juice and the like. There has been a long felt and generally unfilled need for mechanical crop harvesters, especially for the fresh fruit market.
2. Description of the Prior Art
In the present day economy, human pickers are paid $7-10 per hour and can usually work about six hours a day, with each picker producing about sixty boxes per day. Citrus trees will yield four to six boxes for small trees and ten to fifteen boxes for large trees. The cost to pick by hand will average about $9 for 10 boxes. The cost of hand picking is quite high and unfortunately, it is becoming difficult to obtain efficient pickers.
The search for a mechanical harvester for citrus has been continuing for many years and many different methods, techniques, and devices have been proposed and attempted. However, all systems or methods involve certain common requirements. A successful system must provide the harvesting functions of selection, detachment, collection, and transport. In the selection process, the harvester must discriminate between ripe, mature fruit and immature fruit, leaves, branches, and the like. After the mature fruit is identified, it must be detached from its physical connection to the tree. Once the fruit is detached, it must be collected from that point and placed in a container for transportation from the grove to the packing house.
Two broad approaches have been developed to mechanical harvesting: mass harvesting; and individual fruit harvesting. Mass harvesting does not discriminate individual fruit and has generally been attempted by the use of limb and tree shakers, tines which project into the trees and oscillate or rotate, or by use of air blasts. The fruit that is detached generally is permitted to fall to the ground or to a canopy under the tree for collection. This often results in fruit damage due to the fruit striking branches and tearing of the abscission layer or the peel, resulting in plugged fruit.
Due to the relatively high rate of fruit injury, and the damage to the trees themselves from the mass harvesting apparatus, this approach has not been successful.
In the individual fruit harvesting approach, each fruit is treated as an entity and means are provided for selecting and detaching each fruit. A number of devices have been proposed and tried for this purpose. For example, U.S. Pat. No. 3,925,973 uses a hollow cylindrical housing having a spiral auger which traps the fruit, severs it, and carries it back to a discharge outlet. A typical vacuum operative fruit harvester is taught in U.S. Pat. No. 4,388,798 in which a picker stands on the ground and extends a conduit into the tree. Suction pulls the fruit into the conduit which includes means for severing the fruit from the stem. French patent 7,528,286 utilizes a manually controlled head having a suction source with a small circular saw for cutting the stem. Many variations to these basic types of devices will be found in the art. However, none have come into general use and one must draw the conclusion that the prior art has failed to provide a successful solution to this approach to mechanical harvesting.